Method of producing side-pocket mandrels free of welds

ABSTRACT

Method of producing side-pocket mandrels free of welds comprising a series of boring and machining steps by mechanical action and/or electro-erosion to produce a mandrel having at least one valve pocket and discriminator.

This invention relates to a method of producing side-pocket mandrelsfree of welds.

Mandrels having offset side pockets with seatings for flow controlvalves to be placed in and removed from the side pockets, are interposedin a string of well tubing, the main bores of the mandrels being alignedwith and generally of the same diameter as the bore of the well tubing.The valves are installed in or removed from the seatings therefor in theside pockets by a valve-handling apparatus or kickover tool, means beingprovided for moving the apparatus through the tubing and mandrels, thelatter accommodating at an upper or lower level therein orientingsleeves adapted to guide the valve-handling apparatus into an attituderelative to the valve seating appropriate for installing a valve thereinor removing a valve therefrom.

Hitherto, in the construction of side-pocket mandrels in the main, awindow has been formed in the side of an elongate tubular body bycutting a segment out of the wall of said body and a fabricated inserthas been substituted for the segment and has been welded in the window.In other constructions adjacent tubular members have been joinedtogether using circumferential butt welds.

The majority of the failures that have occured in side-pocket mandrelsover the years they have been in use have been directly attributable toweld seams giving way to stresses created in the mandrels as result offorces applied thereto during operational use.

The object of the present invention is to provide a method of producingside-pocket mandrels in which welding is entirely dispensed with and theresulting mandrels are free of welds and thus not subject to thefailures hitherto directly attributable to welds.

In accordance with a first aspect of the present invention, a method ofproducing a side-pocket mandrel comprises

(A) Axially boring a cylindrical metal bar of predetermined length anddiameter from each of the two ends thereof to predetermined depths toleave a land between the blind bores;

(B) Boring through said land from end to end thereof to provide a boreof smaller diameter than said blind bores and coaxial with or axiallyoffset from but parallel to said blind bores;

(C) Machining through said land at least one bore which is symmetricalabout a diametrical plane of said smaller bore is of semicircular archperiphery from one end of said land with the plane and parallel flanksthereof penetrating said smaller bore and effectively forming a windowof actuate segmental shape in the periphery of the latter, and continuesinto a full bore of predetermined peripheral shape forming a valvepocket separated from and axially parallel to said smaller bore andemerging from the other end of said land;

(D) Forming holes through said bar in a chordal plane and intersectingsaid valve pocket;

(E) Swaging both ends of the bar to provide end lengths of lesserexternal diameter and axially aligned with said smaller bore;

(F) Trueing the bores in said end lengths to match said smaller bore;and

(G) Machining an orienting sleeve in the mandrel near one end thereof.

In accordance with a second aspect of the present invention, a method ofproducing a side-pocket mandrel comprises

(A) Axially boring a cylindrical metal bar of predetermined length anddiameter from one end thereof to a predetermined depth to leave a landbetween the blind bore and the opposite end of the bar;

(B) Boring through said land from end to end thereof to provide a boreof smaller diameter than said blind bore and coaxial with or axiallyoffset from but parallel to said blind bore;

(C) Machining through said land beyond a predetermined depth from saidopposite end at least one bore which is symmetrical about a diametricalplane of said smaller bore, is of semicircular arch periphery from oneend of said land with the plane and parallel flanks thereof penetratingsaid smaller bore and effectively forming a window of arcuate segmentalshape in the periphery of the latter, and continues into a full bore ofpredetermined peripheral shape forming a valve pocket separated from andaxially parallel to said smaller bore and emerging from the other end ofsaid land into said larger bore;

(D) Forming holes through said bar in a chordal plane and intersectingsaid valve pocket;

(E) Swaging the larger bore end of the bar to provide an end length oflesser external diameter and axially aligned with said smaller bore;

(F) Trueing the bore in said swaged end length to match said smallerbore;

(G) Machining away the land over said predetermined depth from saidopposite end to provide an end length of lesser external diameter;

(H) Machining an orienting sleeve in the mandrel near one end thereof.

In accordance with a third aspect of the present invention, a method ofproducing a side-pocket mandrel comprises

(A) Boring axially offset from end to end leaving a chordal land, acylindrical metal bar of predetermined length and diameter;

(B) Machining through said land beyond a predetermined depth from saidopposite ends at least one bore which is symmetrical about a diametricalplane of said bore, is of semicircular arch periphery from one end ofsaid land with the plane and parallel flanks thereof penetrating saidbore and effectively forming a window of arcuate segmental shape in theperiphery of the latter, and continues into a full bore of predeterminedperipheral shape forming a valve pocket separated from and axiallyparallel to said bore and emerging from the other end of said land;

(C) Forming holes through said bar in a chordal plane and intersectingsaid valve pocket;

(D) Machining away the chordal land over said predetermined depths fromboth ends of the bar to provide end lengths of lesser external diameter;and

(E) Machining an orienting sleeve in the mandrel near one end thereof.

In accordance with a fourth aspect of the present invention, aside-pocket mandrel is produced by one of the methods described innext-preceding three paragraphs. Embodiments of the present inventionwill now be described by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 is a vertical section of a mandrel according to the presentinvention having a pocket with a short discriminator;

FIG. 2 is a vertical section of a mandrel having a pocket with a longdiscriminator;

FIG. 3 is a vertical section of a mandrel having four pockets eachhaving a short discriminator;

FIG. 4 is a vertical cross-section on the line IV--IV of FIG. 1;

FIG. 5 is a vertical cross-section on the line V--V of FIG. 1 or 2;

FIG. 6 is a vertical cross-section on the line VI--VI of FIG. 2;

FIG. 7 is a vertical cross-section on the line VII--VII of FIG. 1, 2 or3;

FIG. 8 is a section on the line VIII--VIII of FIG. 3;

FIG. 9 is a cross-section on the line IX--IX of FIG. 1 or 2;

FIG. 10 is a cross-section on the line X--X of FIG. 3;

FIG. 11 is a cross-section on the line XI--XI of FIG. 3;

FIG. 12 is a cross-section on the line XII--XII of FIG. 3; and

FIG. 13 is a cross-section one the line XIII--XIII of FIG. 3.

In a first embodiment of the present invention, a side pocket mandrel isformed by axially boring a cylindrical bar of metal, for example ofstainless steel or other steels capable of being used in themanufacturing of a mandrel, the bar being of predetermined length anddiameter from each of the two ends thereof to predetermined depths toleave a land between the blind bores 8. A bore 10 of smaller diameterthan said blind bores 8 is formed by boring through said land from endto end thereof. For mandrels with only one side pocket 12, the smallerbore 10 is axially offset from but parallel to said blind bores 8.

A discriminator and valve pocket are formed in the remainder of the landby machining through said land by mechanical action or byelectro-erosion forming firstly a bore 14 which is symmetrical about adiametrical plane of said smaller bore 10 and which is of semi-circulararch periphery from one end of said land with the plane and parallelflanks 18 thereof penetrating said smaller bore 10 and effectivelyforming a window of arcuate segmental shape in the periphery of thesmaller bore 10 thus forming the discriminator and then secondlycontinuing the machining into a full bore of predetermined peripheralshape forming the valve pocket 16 separated from and axially parallel tosaid smaller bore 10 and emerging from the other end of the land. Aseries of holes 20 are formed through the bar wall 22 in a chordal planeand intersecting said valve pocket 16. Both ends of the bar are swagedto provide end lengths 24 of lesser external diameter and axiallyaligned with said smaller bore 10 and the bores in said end lengths 24are trued to match said smaller bore 10. Adjacent to the inside end ofthe end piece next to the discriminator, an orienting sleeve 26 ismachined by mechanical action or electro-erosion, said end to beuppermost or lowermost as required when the side mandrel is operative.

The depth of land left at the first stage after boring into the bar fromboth ends can vary depending on whether a short discriminator (FIG. 1)or long discriminator (FIG. 2) is required.

In a modification, the smaller bore 10 is coaxial with the blind boresand more than one side pocket 12 is formed, for example (FIG. 3) fourspaced at 90 degrees to each other, each pocket having a discriminatorand valve pocket 16 with holes 20.

In a second embodiment, the side pocket mandrel is formed by axiallyboring a cylindrical bar of metal of predetermined length and diameterfrom one end thereof to a predetermined depth to leave a land betweenthe blind bore 8 and the opposite end of the bars. A bore 10 of smallerdiameter than said blind bore 8 is formed by boring through said landfrom end to end thereof. For mandrels with only one side pocket 12, thesmaller bore 10 is axially offset from but parallel to said blind bore8.

A discriminator and valve pocket are formed in the remainder of the landby machining through said land beyond a predetermined depth from saidopposite end by mechanical action or by electro-erosion forming firstlya bore 14 which is symmetrical about a diametrical plane of said smallerbore 10 and which is of semi-circular arch periphery from one end ofsaid land with the plane and parallel flanks 18 thereof penetrating saidsmaller bore 10 and effectively forming a window of arcuate segmentalshape in the periphery of the smaller bore 10 thus forming thediscriminator and then secondly continuing the machining into a fullbore of predetermined peripheral shape forming the valve pocket 16separated from and axially parallel to said smaller bore 10 and emergingfrom the other end of the land into said larger bore. A series of holes20 are formed through the bar wall 22 in a chordal plane and intersectsaid valve pocket 16. The larger bore end of the bar is swaged toprovide an end length 24 of lesser external diameter and axially alignedwith said smaller bore 10 and the bore in said swaged end length 24 istrued to match said smaller bore 10. Adjacent to the inside end of theend piece next to the discriminator, an orienting sleeve 26 is machinedby mechanical action or electro-erosion, said end to be uppermost orlowermost as required when the side mandrel is operative.

The depth of land left at the first stage after boring into the bar fromboth ends can vary depending on whether a short discriminator (FIG. 1)or long discriminator (FIG. 2) is required.

In a modification, the smaller bore 10 is coaxial with the blind boresand more than one side pocket 12 is formed, for example (FIG. 3) fourspaced at 90 degrees to each other, each pocket having a discriminatorand valve pocket 16 with holes 20.

In a third embodiment, the side pocket mandrel is formed by boringaxially offset from end to end leaving a chordal land a cylindrical barof metal of predetermined length and diameter.

A discriminator and valve pocket are formed by machining through saidland beyond a predetermined depth from said opposite ends by mechanicalaction or by electro-erosion forming firstly a bore 14 which issymmetrical about a diametrical plane of said bore 10 and which is ofsemi-circular arch periphery from one end of said land with the planeand parallel flanks 18 thereof penetrating said bore 10 and effectivelyforming a window of arcuate segmental shape in the periphery of the bore10 thus forming the discriminator and then secondly continuing themachining into a full bore of predetermined peripheral shape forming thevalve pocket 16 separated from and axially parallel to said bore 10 andemerging from the other end of the land. A series of holes 20 are formedthrough the bar wall 22 in a chordal plane and intersect said valvepocket 16. The chordal land over said predetermined depths from each endof the bar are machined away to provide end lengths 24 of lesserexternal diameter. Adjacent to the inside end of the end piece next tothe discriminator, an orienting sleeve 26 is machined by mechanicalaction or electro-erosion, said end to be uppermost or lowermost asrequired when the side mandrel is operative.

The predetermined depth of land left at one end at the first stage afterboring into the bar from one end can vary depending on whether a shortdiscriminator (FIG. 1) or long discriminator (FIG. 2) is required.

In a modification, the bore 10 is coaxial with bar and more than oneside pocket 12 is formed, for example (FIG. 3) four spaced at 90 degreesto each other, each pocket having a discriminator and valve pocket 16with holes 20.

I claim:
 1. A method of producing a side-pocket mandrel comprising:(A)axially boring a cylindrical metal bar of predetermined length anddiameter from each of the two ends thereof to predetermined depths toleave a land between the blind bores; (B) boring through said land fromend to end thereof to provide a bore of smaller diameter than said blindbores and coaxial with or axially offset from but parallel to said blindbores; (C) machining through said land at least one bore which issymmetrical about a diametrical plane of said smaller bore is ofsemicircular arch periphery from one end of said land with the plane andparallel flanks thereof penetrating said smaller bore and effectivelyforming a window of actuate segmental shape in the periphery of thelatter, and continues into a full bore of predetermined peripheral shapeforming a valve pocket separated from and axially parallel to saidsmaller bore and emerging from the other end of said land; (D) formingholes through said bar in a chordal plane and intersecting said valvepocket; (E) swaging both ends of the bar to provide end lengths oflesser external diameter and axially aligned with said smaller bore; (F)trueing the bores in said end lengths to match said smaller bore; and(G) machining an orienting sleeve in the mandrel near one end thereof.2. A method of producing a side pocket mandrel comprising:(A) axiallyboring a cylindrical metal bar of predetermined length and diameter fromone end thereof to a predetermined depth to leave a land between theblind bore and the opposite end of the bar; (B) boring through said landfrom end to end thereof to provide a bore of smaller diameter than saidblind bore and coaxial with or axially offset from but parallel to saidblind bore; (C) machining through said land beyond a predetermined depthfrom said opposite end at least one bore which is symmetrical about adiametrical plane of said smaller bore, is of semicircular archperiphery from one end of said land with the plane and parallel flanksthereof penetrating said smaller bore and effectively forming a windowof arcuate segmental shape in the periphery of the latter, and continuesinto a full bore of predetermined peripheral shape forming a valvepocket separated from and axially parallel to said smaller bore andemerging from the other end of said land into said larger bore; (D)forming holes through said bar in a chordal plane and intersecting saidvalve pocket; (E) swaging the larger bore end of the bar to provide anend length of lesser external diameter and axially aligned with saidsmaller bore; (F) trueing the bore in said swaged end length to matchsaid smaller bore; (G) machining away the land over said predetermineddepth from said opposite end to provide an end length of lesser externaldiameter; (H) machining an orienting sleeve in the mandrel near one endthereof.
 3. A method of producing a side-pocket mandrel comprising:(A)boring axially offset from end to end leaving a chordal land, acylindrical metal bar of predetermined length and diameter; (B)machining through said land beyond a predetermined depth from saidopposite ends at least one bore which is symmetrical about a diametricalplane of said bore, is of semicircular arch periphery from one end ofsaid land with the plane and parallel flanks thereof penetrating saidbore and effectively forming a window of arcuate segmental shape in theperiphery of the latter, and continues into a full bore of predeterminedperipheral shape forming a valve pocket separated from and axiallyparallel to said bore and emerging from the other end of said land; (C)forming holes through said bar in a chordal plane and intersecting saidvalve pocket; (D) machining away the chordal land over saidpredetermined depths from both ends of the bar to provide end lengths oflesser external diameter; and (E) machining an orienting sleeve in themandrel near one end thereof.
 4. A side-pocket mandrel free of weldshaving at least one side pocket and discriminator when produced inaccordance with claims 1, 2 or
 3. 5. A side pocket mandrel comprising:anelongate block of material; a swaged end on each end of said elongateblock defining the exterior of the side pocket; a through bore passinglengthwise through said block and being substantially concentric withsaid swaged ends; a valve pocket in said side pocket in said elongateblock parallel to and separated from said through bore; and adiscriminator on one end of said valve pocket that opens said valvepocket into said through bore, thereby providing a weld-free mandrelhaving improved durability.
 6. The side-pocket mandrel claimed in claim5 wherein said valve pocket extends substantially the entire length ofsaid side pocket.
 7. The side-pocket mandrel claimed in claim 5 whereinat least two valve pockets are formed in said mandrel and said throughbore is concentric with the long axis of said block.